The present invention relates to an improved three-pole electrocatheter for permanent cardiac stimulation.
Among the various known methods for permanent electric cardiac stimulation, the method which entails the detection of the spontaneous atrial signal and the consequent activation of the appropriately delayed ventricle stimulation circuit is particularly useful in the treatment of some diseases of the cardiac conduction system.
This stimulation method, known as "atrium-guided" has the invaluable advantage of adapting the ventricular stimulation frequency to the sinus frequency.
In order to perform this stimulation it is therefore necessary to provide both a detection system, suitable for receiving the signal generated by atrial activation, and a system which carries the electric signal, processed by the cardiac stimulator, to the ventricular tissue, with the additional capability, as in the conventional ventricle-inhibited method, of also receiving the ventricular spontaneous activation signal.
In order to perform this stimulation method, three-pole electrocatheters are already in use and are substantially constituted by a flexible body which extends substantially axially; a terminal portion of said body has a ventricular electrode at its end and has, on its own outer surface, a pair of atrial electrodes which are appropriately spaced from one another and with respect to the ventricular electrode.
On the side opposite to the terminal portion, the flexible body is divided into two terminal sections which also extend substantially axially and respectively bear a unipolar pin and a bipolar pin, both of which can be connected to an adapted cardiac stimulator.
The unipolar pin and the bipolar pin are electrically connected, by mutually adjacent and electrically insulated coiled electric conductors which extend inside the flexible body, respectively to the ventricular electrode and to the pair of atrial electrodes in order to receive the spontaneous atrial signal and accordingly stimulate the ventricle.
However, this known electrocatheter is not free from disadvantages, including most of all the fact that the structure of the flexible body, by having three adjacent coiled electric conductors along most of its extension, has a cross-section which is not adequate for all or most applicative requirements.
The fact that it is necessary to provide thickness changes which are as uniform and as carefully blended as possible has furthermore produced a certain complication in the internal structure of the electrocatheter, in particular in the electrode regions, to the detriment of the production process and accordingly of costs.